This application relates to magnetic disc drives and more particularly to an improved voice coil motor (VCM) assembly including a shroud feature.
Disc drives are data storage devices that store digital data in magnetic form on a storage medium on a rotating information storage disc. Modern disc drives include one or more rigid discs that are coated with a magnetizable medium and mounted on the hub of a spindle motor for rotation at a constant high speed. Information is stored on the discs in a plurality of concentric circular tracks typically by an array of transducers (xe2x80x9cheadsxe2x80x9d) mounted to a radial actuator for movement of the heads relative to the discs. Each of the concentric tracks is generally divided into a plurality of separately addressable data sectors. The read/write transducer, e.g., a magneto resistive read/write head, is used to transfer data between a desired track and an external environment. During a write operation, data is written onto the disc track and during a read operation the head senses the data previously written on the disc track and transfers the information to the external environment. Critical to both of these operations is the accurate locating of the head over the center of the desired track.
The heads are mounted via flexures at the ends of a plurality of actuator arms that project radially outward from the actuator body. The actuator body pivots about a shaft mounted to the disc drive housing at a position closely adjacent the outer extreme of the discs. The pivot shaft is parallel with the axis of rotation of the spindle motor and the discs, so that the heads move in a plane parallel with the surfaces of the discs. The radial position of the heads is controlled through the use of a voice coil motor (VCM) assembly positioned adjacent to the disc.
The rotation of the disc at high speeds during operation creates airflow adjacent the disc surfaces. When a large volume of air space is adjacent the rotating disc, this airflow is often turbulent. It is preferable that turbulence in the airflow minimized. Turbulence can effect the radial and vertical positioning of the head over the center of the desired track, and can cause the disc to flutter undesirably.
To reduce the amount of turbulent airflow during operation of the disc, often an inner disc shroud is constructed in the base plate of the disc drive and by structural features to define a minimal disc operation space. The shroud surrounds the disc such that the inner surface of the shroud is in close proximity to the outer peripheral surface of the disc around its circumference to reduce turbulence. It is preferable that the disc shroud enclose as much of the circumference of the outer peripheral surface of the disc as possible, without interfering with other components of the disc drive. However, openings in such a disc shroud are typically provided adjacent the actuator assembly to accommodate the voice coil motor (VCM), accommodate movement of the actuator and allow for proper installation and operational clearances for these components. These openings in the shroud, however, permit turbulence to develop when the disc is rotated.
Against this backdrop the present invention has been developed. The present invention is an apparatus incorporating an airflow shroud feature in a VCM assembly. More particularly, the top pole piece of the VCM incorporates a disc shroud extension feature that is designed to help alleviate turbulence in the disc drive.
In accordance with one preferred embodiment, the invention is implemented as a disc drive having a base plate and an information storage disc supported for rotation by a drive motor on the base plate. The disc drive further includes a rotary actuator assembly mounted on the base plate adjacent the information storage disc. The actuator assembly has an actuator arm carrying a transducer at a distal end thereof and a voice coil motor operably attached to the actuator arm for movement of the transducer over the disc. The voice coil motor has a vertically extending shroud flange positioned adjacent the outer peripheral edge of the disc, whereby the shroud flange directs air-flow along the peripheral edge of the disc during drive operation.
The invention can be implemented in accordance with another preferred embodiment as a voice coil motor assembly for use in a disc drive. The voice coil motor assembly includes a top plate pole piece and a bottom plate pole piece connected together in spaced relation forming a gap, and a voice coil in the gap connected to the actuator. The VCM assembly further includes a pair of magnets in side by side relation on one of the pole pieces in the gap that establish a magnetic field in which the coil is immersed. A vertically projecting shroud flange extends from one of the top plate or the bottom plate toward the other plate adjacent the outer peripheral surface of the disc whereby the shroud directs airflow along the outer peripheral surface of the disc when the disc is operated.
Other features as well as advantages which characterize various embodiments of the present invention will be apparent from a reading of the following detailed description and a review of the associated drawings.